Opening hard mask and SOI substrate in single process chamber

Abstract

Methods for opening a hard mask and a silicon-on-insulator substrate in a single process chamber are disclosed. In one embodiment, the method includes patterning a photoresist over a stack including an anti-reflective coating (ARC) layer, a silicon dioxide (SiO 2 ) based hard mask layer, a silicon nitride pad layer, a silicon dioxide (SiO 2 ) pad layer and the SOI substrate, wherein the SOI substrate includes a silicon-on-insulator layer and a buried silicon dioxide (SiO 2 ) layer; and in a single process chamber: opening the ARC layer; etching the silicon dioxide (SiO 2 ) based hard mask layer; etching the silicon nitride pad layer; etching the silicon dioxide (SiO 2 ) pad layer; and etching the SOI substrate. Etching all layers in a single chamber reduces the turn-around-time, lowers the process cost, facilitates process control and/or improve a trench profile.

1. A method of opening a hard mask and a silicon-on-insulator (SOI) substrate, the method comprising the steps of:
 patterning a photoresist over a stack including an anti-reflective coating (ARC) layer, a silicon dioxide (SiO 2 ) based hard mask layer, a silicon nitride pad layer, a silicon dioxide (SiO 2 ) pad layer and the SOI substrate, wherein the SOI substrate includes a silicon-on-insulator (SOI) layer and a buried silicon dioxide (SiO 2 ) layer; and 
 in a single process chamber:
 opening the ARC layer; 
 etching the silicon dioxide (SiO 2 ) based hard mask layer; 
 etching the silicon nitride pad layer; 
 etching the silicon dioxide (SiO 2 ) pad layer; and 
 etching the SOI substrate, wherein the etch chemistry for etching the SOI substrate includes:
 using approximately 80-100 standard cubic centimeters per minute (sccm) of difluoromethane (CH 2 F 2 ), approximately 35-45 sccm of tetrafluoromethane (CF 4 ) approximately 25-30 sccm of oxygen (O 2 ) and approximately 180-220 sccm of nitrogen (N 2 ) for the SOI layer; and 
 using approximately 10-30 sccm oxygen (O 2 ) 10-40 sccm hexafluorobutadiene (C 4 F 6 ) and 900-1200 sccm argon (Ar) for the buried silicon dioxide (SiO 2 ) layer. 
 
 
 
   
   
     2. The method of  claim 1 , wherein the etch chemistry for the SOI layer includes: approximately 90 sccm of difluoromethane (CH 2 F 2 ), approximately 40 sccm of tetrafluoromethane (CF 4 ), approximately 27 sccm of oxygen (O 2 ) and approximately 200 sccm of nitrogen (N 2 ). 
   
   
     3. The method of  claim 1 , wherein the SOI substrate etching step further includes overetching into a bulk silicon substrate under the SOI substrate. 
   
   
     4. The method of  claim 3 , wherein the overetching step includes using approximately 80-100 standard cubic centimeters per minute (sccm) of difluoromethane (CH 2 F 2 ), approximately 35-45 sccm of tetrafluoromethane (CF 4 ), approximately 25-30 sccm of oxygen (O 2 ) and approximately 180-220 sccm of nitrogen (N 2 ). 
   
   
     5. The method of  claim 1 , wherein the ARC layer opening step includes etching using approximately 100-200 standard cubic centimeters per minute (sccm) of tetrafluoromethane (CF 4 ) with a power of 400-700 Watts and a pressure of 50-150 milli-Torr. 
   
   
     6. The method of  claim 1 , wherein the silicon dioxide (SiO 2 ) based hard mask layer etching step includes using 10-30 standard cubic centimeters per minute (sccm) oxygen (O 2 ), 10-40 sccm hexafluorobutadiene (C 4 F 6 ) and 900-1200 sccm argon (Ar). 
   
   
     7. The method of  claim 1 , wherein the silicon nitride pad layer and the silicon dioxide (SiO 2 ) pad layer etching steps include using 50-100 standard cubic centimeters per minute (sccm) difluoromethane (CH 2 F 2 ), 10-40 sccm oxygen (O 2 ), 40-80 sccm tetrafluoromethane (CF 4 ) and 400-1000 sccm argon (Ar). 
   
   
     8. A method of opening a hard mask and a silicon-on-insulator (SOI) substrate, the method comprising the steps of:
 patterning a photoresist over a stack including an anti-reflective coating (ARC) layer, a silicon dioxide (SiO 2 ) based hard mask layer, a silicon nitride pad layer, a silicon dioxide (SiO 2 ) pad layer and the SOI substrate, wherein the SOI substrate includes a silicon-on-insulator (SOI) layer and a buried silicon dioxide (SiO 2 ) layer; and 
 in a single process chamber:
 opening the ARC layer; 
 etching the silicon dioxide (SiO 2 ) based hard mask layer; 
 etching the silicon nitride pad layer; 
 etching the silicon dioxide (SiO 2 ) pad layer; and 
 etching the SOI substrate using an etch chemistry including:
 approximately 90 standard cubic centimeters per minute (sccm) of difluoromethane (CH 2 F 2 ), approximately 40 sccm of tetrafluoromethane (CF 4 ), approximately 27 sccm of oxygen (O 2 ) and approximately 200 sccm of nitrogen (N 2 ) for the SOI layer. 
 
 
 
   
   
     9. The method of  claim 8 , wherein the SOI substrate etching step further includes using approximately 10-30 sccm oxygen (O 2 ), 10-40 sccm hexafluorobutadiene (C 4 F 6 ) and 900-1200 sccm argon (Ar) for the buried silicon dioxide (SiO 2 ) layer. 
   
   
     10. The method of  claim 8 , wherein the SOI substrate etching step further includes overetching into a bulk silicon substrate under the SOI substrate. 
   
   
     11. The method of  claim 10 , wherein the overetching step includes using approximately 80-100 sccm of difluoromethane (CH 2 F 2 ), approximately 35-45 sccm of tetrafluoromethane (CF 4 ), approximately 25-30 sccm of oxygen (O 2 )and approximately 180-220 sccm of nitrogen (N 2 ). 
   
   
     12. The method of  claim 8 , wherein the ARC layer opening step includes etching using approximately 100-200 sccm of tetrafluoromethane (CF 4 ) with a power of 400-700 Watts and a pressure of 50-150 milli-Torr. 
   
   
     13. The method of  claim 8 , wherein the silicon dioxide (SiO 2 ) based hard mask layer etching step includes using 10-30 sccm oxygen (O 2 ), 10-40 sccm hexafluorobutadiene (C 4 F 6 ) and 900-1200 sccm argon (Ar). 
   
   
     14. The method of  claim 8 , wherein the silicon nitride pad layer and the silicon dioxide (SiO 2 ) pad layer etching steps include using 50-100 sccm difluoromethane (CH 2 F 2 ), 10-40 sccm oxygen (O 2 ), 40-80 sccm tetrafluoromethane (CF 4 ) and 400-1000 sccm argon (Ar). 
   
   
     15. A method of opening a hard mask and a silicon-on-insulator (SOI) substrate, the method comprising the steps of:
 providing a stack including an anti-reflective coating (ARC) layer, a silicon dioxide (SiO 2 ) based hard mask layer, a silicon nitride pad layer, a silicon dioxide (SiO 2 ) pad layer and the SOI substrate, wherein the SOI substrate includes a silicon-on-insulator (SOI) layer and a buried silicon dioxide (SiO 2 ) layer; 
 patterning a photoresist over the stack; and 
 in a single process chamber:
 opening the ARC layer; 
 etching the silicon dioxide (SiO 2 ) based hard mask layer; 
 etching the silicon nitride pad layer; 
 etching the silicon dioxide (SiO 2 ) pad layer; and 
 etching the SOI substrate using an etch chemistry including:
 approximately 90 standard cubic centimeters per minute (sccm) of difluoromethane (CH 2 F 2 ), approximately 40 sccm of tetrafluoromethane (CF 4 ), approximately 27 sccm of oxygen (O 2 ) and approximately 200 sccm of nitrogen (N 2 ) for the SOI layer, and 
 approximately 10-30 sccm oxygen (O 2 ), 10-40 sccm hexafluorobutadiene (C 4 F 6 ) and 900-1200 sccm argon (Ar) for the buried silicon dioxide (SiO 2 ) layer. 
 
 
 
   
   
     16. The method of  claim 15 , wherein the SOI substrate etching step further includes overetching into a bulk silicon substrate under the SOI substrate. 
   
   
     17. The method of  claim 16 , wherein the overetching step includes using approximately 80-100 sccm of difluoromethane (CH 2 F 2 ), approximately 35-45 sccm of tetrafluoromethane (CF 4 ), approximately 25-30 sccm of oxygen (O 2 ) and approximately 180-220 sccm of nitrogen (N 2 ). 
   
   
     18. The method of  claim 15 , wherein the ARC layer opening step includes etching using approximately 100-200 sccm of tetrafluoromethane (CF 4 ) with a power of 400-700 Watts and a pressure of 50-150 milli-Torr. 
   
   
     19. The method of  claim 15 , wherein the silicon dioxide (SiO 2 ) based hard mask layer etching step includes using 10-30 sccm oxygen (O 2 ), 10-40 sccm hexafluorobutadiene (C 4 F 6 ) and 900-1200 sccm argon (Ar), and the silicon nitride pad layer and the silicon dioxide (SiO 2 ) pad layer etching steps include using 50-100 sccm difluoromethane (CH 2 F 2 ), 10-40 sccm oxygen (O 2 ), 40-80 sccm tetrafluoromethane (CF 4 ) and 400-1000 sccm argon (Ar).